During some years requirements for the sterilization of surgical instruments have been intensified due to increased knowledge of the risks of infection in public health and sick care. The HIV-problems contribute to the enforcement of stricter requirements for sterilization, especially of instruments for rectal use.
Surgical instruments which are utilized to devitalize tissues, such as internal hemorrhoids, by ligation, a so-called elastic ligature, represent one type of proctologic instrument which is affected by these stricter requirements for sterilization. Different types of instrument for ligating of internal hemorrhoids are known. Most of these instruments are meant to be used several times, that is, they are designated to be re-utilized several times with a sterilization in between.
Instruments suitable for one-time use, i.e. disposable instruments, are also known. For example, EP 0 310 582 by the same applicant discloses a disposable surgical instrument of the above-discussed type.
However, the prior art solutions are all affected by one or several of the following drawbacks and problems:                they are relatively complicated and expensive to produce, which is especially disadvantageous for disposable instruments. Especially, the known devices have constructions which contain a large number of interacting parts, and with complicated transmission mechanism between the activating element and the discharge member;        some known instruments necessitate interaction with a gripping instrument, which makes the operation difficult, since the operating surgeon must use both hands, one for the instrument and the other for the assisting tool; and        some known instruments are relatively un-ergonomic and difficult to handle, thus making the surgeons job more difficult and hazardous.        
There is therefore a need for a surgical instrument of the above-discussed type, having a less complicated construction, and especially for use as a disposable.